Oil cooler

ABSTRACT

An oil cooler including a plurality of core plates stacked on each other, the plurality of core plates each including a base wall and a circumferential wall formed along an entire outer periphery of the base wall, and oil passages and cooling water passages alternately arranged in the direction of stacking the core plates. The core plates include at least a first core plate and a second core plate that is different from the first core plate in construction. The circumferential wall of the second core plate has a height being varied along a circumferential direction of the base wall. The circumferential wall of the second core plate is partially higher than the circumferential wall of the first core plate.

BACKGROUND OF THE INVENTION

The present invention relates to a so-called stacked multi-plate oil cooler that is used for cooling a vehicular oil, for instance, a lubricating oil in an internal combustion engine or a working oil in an automatic transmission.

Japanese Patent Application Unexamined Publication No. 11-351778 discloses an oil cooler including a plurality of first plates and a plurality of second plates which are alternately stacked. A cooling water chamber and an oil chamber are alternately formed between the first plate and the second plate in a direction of stacking the plates. The oil chambers adjacent to each other in the direction of stacking the plates are communicated with each other through a pair of oil passages which are formed in the first plate and the second plate, respectively. The cooling water chambers adjacent to each other in the direction of stacking the plates are communicated with each other through a pair of cooling water passages which are formed in the first plate and the second plate, respectively. A part of each of the oil passages is closed by a given closing plate.

In the above conventional art, a projection or a recess is formed on an outer circumferential periphery of a cylindrical wall of each of the closing plate and the first plate. The projection or the recess is arranged in a certain positional relationship to the oil passages and the cooling water passages. With the provision of the projection or the recess, it is possible to recognize that the first plates and the closing plates are stacked on each other in a certain positional relationship to each other by visual observation from an outside of the oil cooler.

SUMMARY OF THE INVENTION

However, in the above-described conventional art, in a case where the projection is formed on the outer circumferential periphery of each of the closing plate and the first plate, the projection projects from the outer circumferential periphery of each of the closing plate and the first plate. Therefore, there is a possibility that a person who handles the oil cooler is accidentally injured. On the other hand, in a case where the recess is formed on the outer circumferential periphery of each of the closing plate and the first plate, there is also a possibility that a person who handles the oil cooler is accidentally injured with a corner edge of the recess. Further, in such a case, the recess is formed in such a manner as to cut out a portion of the outer circumferential periphery of the cylindrical wall of each of the closing plate and the first plate. Due to the thus formed recess, there will occur reduction in strength of the cylindrical wall in a position in which the recess is formed, and deterioration in anticorrosion property.

It is an object of the present invention to solve the above-described problems encountered in the technologies of the conventional art.

In a first aspect of the present invention, there is provided an oil cooler including:

a plurality of core plates stacked on each other, the plurality of core plates each including a base wall and a circumferential wall formed along an entire outer periphery of the base wall, the circumferential wall being inclined relative to the base wall so as to outwardly extend from the entire outer periphery of the base wall, the circumferential walls of the core plates which are disposed adjacent to each other in a direction of stacking the core plates being bonded to each other, and

oil passages and cooling water passages alternately arranged in the direction of stacking the core plates, the respective oil passages and the respective cooling water passages being formed in a clearance between the base walls adjacent to each other in the direction of stacking the core plates,

wherein the core plates include at least a first core plate and a second core plate that is different from the first core plate in construction, and the circumferential wall of the second core plate has a height being varied along a circumferential direction of the base wall, and the circumferential wall of the second core plate is partially higher than the circumferential wall of the first core plate.

In a second aspect of the present invention, there is provided the oil cooler according to the first aspect of the present invention, wherein the height of the circumferential wall of the second core plate is continuously varied along the entire outer periphery of the base wall, and the circumferential wall of the second core plate has an upper end located on a plane.

In a third aspect of the present invention, there is provided the oil cooler according to the first aspect of the present invention, wherein the base wall of the first core plate includes a pair of oil communication holes through which the oil passages are communicated with each other in the direction of stacking the core plates, and a pair of cooling water communication holes through which the cooling water passages are communicated with each other in the direction of stacking the core plates, the pair of oil communication holes being symmetrically arranged with respect to a center of the base wall,

the circumferential wall of the first core plate has a constant height over the entire outer periphery of the base wall of the first core plate, and

the base wall of the second core plate comprises one oil communication hole aligned with one of the pair of oil communication holes of the base wall of the first core plate, the base wall of the second core plate blocking a flow of oil passing through the other of the pair of oil communication holes of the base wall of the first core plate such that a direction of a flow of oil passing through the oil cooler is changed to a direction perpendicular to the direction of stacking the core plates.

The oil cooler according to the present invention can serve for identifying a specific core plate on the basis of a difference in height of a peripheral wall between a plurality of core plates even after the core plates are stacked on each other. Further, a person who handles the oil cooler according to the present invention can be prevented from suffering an injury due to a configuration of the identifying portion of the core plate. Furthermore, the oil cooler according to the present invention can serve for suppressing reduction in strength of the specific core plate to be identified and deterioration of anticorrosion property.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an oil cooler according to a first embodiment of the present invention.

FIG. 2 is a plan view of the oil cooler according to the first embodiment of the present invention.

FIG. 3 is a sectional view of the oil cooler according to the first embodiment of the present invention, taken along line A-A shown in FIG. 2.

FIG. 4 is a perspective view of a second core plate used in the oil cooler according to the first embodiment of the present invention.

FIG. 5 is a side view of the second core plate shown in FIG. 4, when viewed from a direction of arrow B shown in FIG. 4.

FIG. 6 is a perspective view of the oil cooler according to the first embodiment of the present invention.

FIG. 7 is a side view of the oil cooler according to the first embodiment of the present invention.

FIG. 8 is a perspective view of a second core plate used in an oil cooler according to a second embodiment of the present invention.

FIG. 9 is a side view of the second core plate shown in FIG. 8, when viewed from a direction of arrow C shown in FIG. 8.

FIG. 10 is a side view of the oil cooler according to the second embodiment of the present invention.

FIG. 11 is a perspective view of a second core plate used in an oil cooler according to a third embodiment of the present invention.

FIG. 12 is a side view of the second core plate shown in FIG. 11, when viewed from a direction of arrow D shown in FIG. 11.

FIG. 13 is a side view of the second core plate shown in FIG. 11, when viewed from a direction of arrow E shown in FIG. 11.

FIG. 14 is a side view of the oil cooler according to the third embodiment of the present invention.

FIG. 15 is a perspective view of a second core plate used in an oil cooler according to a fourth embodiment of the present invention.

FIG. 16 is a side view of the second core plate shown in FIG. 15, when viewed from a direction of arrow F shown in FIG. 15.

FIG. 17 is a side view of the oil cooler according to the fourth embodiment of the present invention.

FIG. 18 is a perspective view of a second core plate used in the oil cooler according to a fifth embodiment of the present invention.

FIG. 19 is a side view of the second core plate shown in FIG. 18, when viewed from a direction of arrow G shown in FIG. 18.

FIG. 20 is side view of an oil cooler according to the fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An oil cooler 100 according to a first embodiment of the present invention will be explained hereinafter by referring to FIG. 1 to FIG. 7.

FIG. 1 is an exploded perspective view of the oil cooler 100. FIG. 2 is a plan view of the oil cooler 100. FIG. 3 is a sectional view of the oil cooler 100, taken along line A-A shown in FIG. 2

A construction of the oil cooler 100 as a whole is explained. The oil cooler 100 is entirely made of aluminum, for example. As shown in FIG. 1, the oil cooler 100 includes a core module 1 that performs heat exchange between oil and cooling water, a top plate 2 that is mounted to a top surface of the core module 1 and has a relatively large thickness, and a bottom plate 3 mounted to a bottom surface of the core module 1.

The core module 1 includes four kinds of core plates 4, 5, 6, 7 which basically have substantially the same shape and are stacked on each other in a predetermined order. The core module 1 also includes oil passages 8 and cooling water passages 9 alternately arranged in a direction of stacking the core plates 4, 5, 6, 7 (hereinafter simply referred to as a core plate stacking direction). In the embodiment shown in FIG. 1, the core module 1 is formed by alternately stacking a first basic core plate 4 and a second basic core plate 5 on each other, each serving as a first core plate, except that the first basic core plates 4 disposed in two intermediate positions of the core module 1 in the core plate stacking direction are each replaced by a second core plate 6. A third core plate 7 is disposed on an upper-most portion of the core module 1. A generally rectangular fin plate 10 is disposed in the respective oil passages 8.

The first basic core plate 4 and the second basic core plate 5 have a generally rectangular shape in plan view. A pair of oil communication holes 11 are formed on one of diagonal lines of each of the first and second basic core plates 4, 5 in a spaced relation to each other. A pair of cooling water communication holes 12 are formed on the other diagonal line of each of the first and second basic core plates 4, 5 in a spaced relation to each other.

Specifically, the first basic core plate 4 includes a rectangular plate-shaped base wall 4 a, and an inclined circumferential wall 4 b that is formed along an entire outer periphery of the base wall 4 a and inclined so as to outwardly extend from an outer circumferential edge of the base wall 4 a. The base wall 4 a is formed with the pair of oil communication holes 11, 11 and the pair of cooling water communication holes 12, 12 which extend through the base wall 4 a. The base wall 4 a is also formed with a tapered sleeve portion 4 c that is formed along an entire periphery of a central through hole of the base wall 4 a so as to have a hollow frustoconical shape. A boss 13 is formed along an entire periphery of the respective cooling water communication holes 12, 12. The second basic core plate 5 includes a rectangular plate-shaped base wall 5 a, and an inclined circumferential wall 5 b that is formed along an entire outer periphery of the base wall 5 a and inclined so as to outwardly extend from an outer circumferential edge of the base wall 5 a. The base wall 5 a is formed with the pair of oil communication holes 11, 11 and the pair of cooling water communication holes 12, 12 which extend through the base wall 5 a. The base wall 5 a is also formed with a tapered sleeve portion 5 c that is formed along an entire periphery of a central through hole of the base wall 5 a so as to have a hollow frustoconical shape, and a plurality of frustoconical projections 14 upwardly projecting from the base wall 5 a. A boss 15 is formed along an entire periphery of the respective oil communication holes 11, 11. The boss 15 has a same height as that of the boss 13 of the first basic core plate 4.

The second core plate 6 has a generally rectangular shape in plan view. A pair of cooling water communication holes 12, 12 are formed on one of diagonal lines of the second core plate 6 in a spaced relation to each other. One oil communication hole 11 is formed on the other diagonal line of the second core plate 6.

Specifically, the second core plate 6 includes a rectangular plate-shaped base wall 6 a, and an inclined circumferential wall 6 b that is formed along an entire outer periphery of the base wall 6 a and inclined so as to outwardly extend from an outer circumferential edge of the base wall 6 a. The base wall 6 a is formed with the one oil communication hole 11 and the pair of cooling water communication holes 12, 12 which extend through the base wall 6 a. The base wall 6 a is also formed with a tapered sleeve portion 6 c that is formed along an entire periphery of a central through hole of the base wall 6 a so as to have a hollow frustoconical shape. A boss 13 is formed along an entire periphery of the respective cooling water communication holes 12, 12. The boss 13 has a height equal to that of the boss 13 of the first basic core plate 4. In other words, the base wall 6 a of the second core plate 6 in this embodiment has the same configuration as that of the base wall 4 a of the first basic core plate 4 except that one of the pair of oil communication holes 11, 11 is closed.

The third core plate 7 has a generally rectangular shape in plan view. A pair of cooling water communication holes 12, 12 are formed on one of diagonal lines of the third core plate 7 in a spaced relation to each other. One oil communication hole 11 is formed on the other diagonal line of the third core plate 7.

Specifically, the third core plate 7 includes a rectangular plate-shaped base wall 7 a, and an inclined circumferential wall 7 b that is formed along an entire outer periphery of the base wall 7 a and inclined so as to outwardly extend from an outer circumferential edge of the base wall 7 a. The base wall 7 a is formed with the oil communication hole 11 and the pair of cooling water communication holes 12, 12 which extend through the base wall 7 a. The base wall 7 a is also formed with a tapered sleeve portion 7 c that is formed along an entire periphery of a central through hole of the base wall 7 a so as to have a hollow frustoconical shape. Owing to the positional relationship with the top plate 2, the third core plate 7 has no boss formed around each of the oil communication hole 11 and the cooling water communication holes 12, 12.

In a stacked condition in which the respective core plates 4, 5, 6, 7 are stacked on each other, the circumferential walls 4 b, 5 b, 6 b, 7 b are overlapped and closely contacted with each other in the core plate stacking direction. Further, in the stacked condition, the tapered sleeve portions 4 c, 5 c, 6 c, 7 c are stacked on each other to form a central oil passage 16 extending through the core module 1 in a vertical direction (i.e., in the core plate stacking direction). The central oil passage 16 is not directly communicated with the respective oil passages 8 formed between the core plates 4, 5, 6, 7.

In the first basic core plate 4 and the second core plate 6, a circumferential portion that defines the respective cooling water communication holes 12, 12 is raised from the respective base walls 4 a and 6 a so as to serve as the boss 13 projecting toward a side of the oil passages 8. In the second basic core plate 5, a circumferential portion that defines the respective oil communication holes 11, 11 is raised from the base wall 5 a so as to serve as the boss 15 projecting toward a side of the cooling water passages 9. With the provision of the basses 13, 15, when these three kinds of the core plates 4, 5, 6 are stacked on each other in combination thereof, predetermined clearances are respectively formed between the base wall 4 a of the first basic core plate 4 and the base wall 5 a of the second basic core plate 5 and between the base wall 5 a of the second basic core plate 5 and the base wall 6 a of the second core plate, serving as the oil passages 8 and the cooling water passages 9.

In the stacked condition in which the multiple core plates 4, 5, 6 are stacked and bonded to each other, a circumferential portion that defines the respective oil communication holes 11 of the first basic core plate 4 is contacted with the boss 15 formed around the respective oil communication holes 11 of the second basic core plate 5 disposed adjacent to the first basic core plate 4. Similarly, in the stacked condition, a circumferential portion that defines the respective oil communication holes 11 of the second core plate 6 is bonded to the boss 15 formed around the respective oil communication holes 11 of the second basic core plate 5 disposed adjacent to the second core plate 6. With this construction, the respective two oil passages 8 aligned with each other in the core plate stacking direction are communicated with each other through the oil communication holes 11, and isolated from the cooling water passage 9 disposed between the respective two oil passages 8. Accordingly, in the stacked condition, the respective oil passages 8 can be communicated with each other through the multiple oil communication holes 11, and the oil is allowed to flow through the whole core module 1 in the vertical direction (i.e., in the core plate stacking direction). Further, in this embodiment, in the stacked condition, the base wall 6 a of the second core plate 6 blocks a flow of oil passing through the other of the pair of oil communication holes 11 of the base walls 4 a, 5 a of the core plates 4, 5 in the vertical direction such that the oil is allowed to flow around rightward and leftward in a U-turn manner toward the one oil communication hole 11 of the base wall 6 a of the second core plate 6. In other words, in a vertical position of the core module 1 in which the second core plate 6 is located, a direction of a flow of the oil passing through the core module 1 is changed to a direction perpendicular to the core plate stacking direction.

The cooling water communication holes 12 are configured similarly to the oil communication holes 11. That is, in the stacked condition, a circumferential portion that defines the respective cooling water communication holes 12 of the second basic core plate 5 is contacted with the boss 13 formed around the respective cooling water communication holes 12 of the first basic core plate 4 or the second core plate 6 which is disposed adjacent to the second basic core plate 5. With this construction, the respective two cooling water passages 9 aligned with each other in the core plate stacking direction are communicated with each other through the cooling water communication holes 12, and isolated from the oil passage 8 disposed between the respective two cooling water passages 9. Accordingly, in the stacked condition in which the multiple core plates 4, 5, 6 are stacked on and bonded to each other, the respective cooling water passages 9 can be communicated with each other through the multiple cooling water communication holes 12, and the cooling water is allowed to flow through the whole core module 1 in the vertical direction (i.e., in the core plate stacking direction).

The projections 14 upwardly swelling from the base wall 5 a of the second basic core plate 5 are formed on the same side as the side on which the circumferential wall 5 b and the tapered sleeve portion 5 c of the second basic core plate 5 are upwardly raised from the base wall 5 a. Further, the respective projections 14 have a generally frustoconical shape and a height equal to that of the bosses 13 of the first basic core plate 4 and the second core plate 6 and that of the bosses 15 of the second basic core plate 5. With this construction, in an assembled condition of the oil cooler 100, as shown in FIG. 3, a top portion of the respective projections 14 is bonded to a lower surface (a flat surface) of the first basic core plate 4 or a lower surface (a flat surface) of the second core plate 6 by brazing.

The fin plate 10 disposed within the respective oil passages 8 includes four openings 17 of which one pair of the openings 17 are formed on one of diagonal lines of the fin plate 10 while the other pair of the openings 17 are formed on the other of the diagonal lines corresponding to the oil communication holes 11 and the cooling water communication holes 12, respectively. The fin plate 10 also includes a through hole 18 formed in a central portion of the fin plate 10 corresponding to the central oil passage 16 formed by the tapered sleeve portions 4 c, 5 c, 6 c, 7 c. The respective openings 17 has a diameter slightly larger than the respective communication holes 11, 12 so as to have a slight allowance relative to the respective bosses 13. Meanwhile, FIG. 1 shows a schematic perspective view of the fin plate 10, and actually, the fin plate 10 is a so-called fin configuration as a whole having a plurality of plate fins.

The top plate 2 is stacked on the upper-most portion of the core module 1, i.e., on an upper surface of the third core plate 7. The top plate 2 includes a cooling water introducing tube 21 communicated with one of the pair of cooling water communication holes 12, 12 located on the upper-most portion of the core module 1, and a cooling water discharging tube 22 communicated with the other of the pair of cooling water communication holes 12, 12. The top plate 2 also includes a swelling portion 23 on an upper side thereof which upwardly swells along one of diagonal lines of the top plate 2 having a generally rectangular shape in plan view. As shown in FIG. 3, the swelling portion 23 defines a communication passage 24 through which the oil communication hole 11 and an upper end of the central oil passage 16 which are located in the upper-most portion of the core module 1 are communicated with each other.

The bottom plate 3 that has a relatively large thickness and a sufficient rigidity is stacked on the lower surface of the core module 1, i.e., on the lower surface of the first basic core plate 4 disposed at the lower-most positions among the whole first basic core plates 4 in the core module 1. The bottom plate 3 includes an oil inlet 25 formed corresponding to one of the pair of oil communication holes 11 located in a lower-most portion of the core module 1, and an oil outlet 26 formed corresponding to the central oil passage 16. The bottom plate 3 is mounted to a cylinder block or the like, not shown.

In the thus constructed oil cooler 100, the oil whole temperature is increased during use for lubrication of respective parts of an internal combustion engine is introduced from the internal combustion engine into the respective oil passages 8 of the core module 1 through the oil inlet 25 of the bottom plate 3, and cooled by heat exchange with the cooling water flowing in the cooling water passages 9 adjacent to the oil passages 8. The oil thus cooled is flowed into the central oil passage 16 through the communication passage 24 of the swelling portion 23 of the top plate 2, and finally is returned to the internal combustion engine through the oil outlet 26 of the bottom plate 3. Meanwhile, the oil cooler may be constructed such that the oil flow is reversed. In such a case, the oil having a high temperature is introduced into the central oil passage 16, and then cooled in the core module 1 by heat exchange. After that, the oil cooled is returned to the internal combustion engine through the oil communication holes 11 located in the lower-most portion of the core module 1. Further, the cooling water is introduced into the core module 1 through the cooling water introducing tube 21. The cooling water is distributed into the respective cooling water passages 9 through the cooling water communication holes 12 aligned with each other in the vertical direction, and at the same time, the cooling water is flowed, in each cooling water passage 9, from one of the pair of cooling water communication holes 12 toward the other cooling water communication hole 12. The cooling water is finally flowed out of the oil cooler 100 through the cooling water discharging tube 22.

The multiple core plates 4, 5, 6, 7, the fin plate 10, the top plate 2 and the bottom plate 3 are bonded to each other by brazing and formed into an integral unit. Specifically, these parts are formed of a so-called clad material that is an aluminum alloy mother metal covered with a brazing metal layer, and are integrally brazed by placing the parts provisionally assembled in predetermined positions within a furnace and heating the thus assembled parts together in the furnace.

Next, the second core plate 6 as an essential part of the oil cooler 100 according to the first embodiment of the present invention will be explained hereinafter. The circumferential wall 6 b of the second core plate 6 is formed such that a portion of the circumferential wall 6 b has a height larger than heights of the circumferential wall 4 b of the first basic core plate 4, the circumferential wall 5 b of the second basic core plate 5, and the circumferential wall 7 b of the third core plate 7. In other words, the second core plate 6 is formed such that the height of the circumferential wall 6 b is varied along a circumferential direction of the base wall 6 a.

That is, the circumferential wall 4 b of the first basic core plate 4, the circumferential wall 5 b of the second basic core plate 5 and the circumferential wall 7 b of the third core plate 7 have a constant height over the entire outer periphery of the respective base walls 4 a, 5 a, 7 a. On the other hand, the circumferential wall 6 b of the second core plate 6 is formed such that a height at one of four corner portions of the circumferential wall 6 b on the side of the oil communication hole 11 is larger than the height of the respective circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7.

Specifically, as shown in FIG. 4, the circumferential wall 6 b of the second core plate 6 has two pairs of diagonally opposed corner portions 31 a, 31 b and 31 c, 31 d. One of the pair of diagonally opposed corner portions 31 a, 31 b, i.e., the corner portion 31 b which is located on the side of the oil communication hole 11 has a height larger than the height of the respective circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7. In contrast, the other corner portion 31 a which is not located on the side of the oil communication hole 11 has a height equal to the height of the respective circumferential walls 4 b, 5 b, 7 b.

More specifically, as shown in FIG. 4 and FIG. 5, the height of the circumferential wall 6 b of the second core plate 6 is varied along the circumferential direction of the base wall 6 a. A plane on which an upper end of the circumferential wall 6 b is located is inclined relative to a plane P parallel with the base wall 6 a. The circumferential wall 6 b has a maximum height at one corner portion 31 b of the pair of diagonally opposed corner portions 31 a, 31 b which is located on the side of the oil communication hole 11. The circumferential wall 6 b has a minimum height at the other corner portion 31 a of the pair of diagonally opposed corner portions 31 a, 31 b which is equal to the height of the respective circumferential walls 4 b, 5 b, 7 b. The circumferential wall 6 b has a height smaller than the maximum height and larger than the minimum height at the pair of diagonally opposed corner portions 31 c, 31 d located on the side of the cooling water communication holes 12, respectively. The height at the corner portion 31 c and the height at the corner portion 31 d are equal to each other.

In the oil cooler 100 using the thus configured second core plate 6, as shown in FIG. 6 and FIG. 7, it is possible to readily recognize a position of the second core plate 6 from an outer appearance thereof even after brazing. Further, since the circumferential wall 6 b has the maximum height at the portion located on the side of the corner portion 31 b formed with the oil communication hole 11, a direction of the second core plate 6 in the core module 1 can be readily recognized from the outer appearance of the oil cooler 100. Furthermore, it is possible to recognize a position of the oil communication hole 11 in the second core plate 6 from the outer appearance of the oil cooler 100.

Further, since the circumferential wall 6 b of the second core plate 6 has the height continuously varied along the entire outer periphery of the base wall 6 a, it is possible to readily recognize that the height of the circumferential wall 6 b is varied when the circumferential wall 6 b is viewed from any position in a circumferential direction of the core module 1.

Furthermore, the second core plate 6 as a specific core plate can be recognized on the basis of the difference in height between the circumferential wall 6 b and the circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7. Accordingly, a person who handles the oil cooler can be prevented from being injured due to a shape or configuration of a portion serving for recognition unlike the conventional art in which a recess or a projection is provided on the specific core plate. Further, a specific core plate to be recognized can be prevented from being deteriorated in strength and anticorrosion property thereof unlike the conventional art requiring the provision of recess or projection serving for recognition of the specific core plate.

Referring to FIG. 8 to FIG. 10, an oil cooler 200 according to a second embodiment of the present invention is explained. The oil cooler 200 has the same construction as that of the above-described oil cooler 100 of the first embodiment except for configuration of a second core plate 206. Like reference numerals denote like parts, and therefore, detailed explanations thereof are omitted.

As shown in FIG. 8 and FIG. 9, a height of the circumferential wall 6 b of the second core plate 206 in the second embodiment is varied along the circumferential direction of the base wall 6 a such that among two pairs of diagonally opposed corner portions 31 a, 31 b and 31 c, 31 d, the height at one corner portion 31 b of the pair of diagonally opposed corner portions 31 a, 31 b which is located on the side of the oil communication hole 11 and the height at the pair of diagonally opposed corner portions 31 c, 31 d respectively located on the side of the cooling water communication holes 12 are largest and equal to each other, and the height at the other corner portion 31 a of the pair of diagonally opposed corner portions 31 a, 31 b is smallest. That is, the circumferential wall 6 b of the second core plate 206 is formed such that among the four corner portions 31 a, 31 b, 31 c, 31 d, one corner portion 31 a (i.e., one of the pair of diagonally opposed corner portions 31 a, 31 b) which is not located on the side of the oil communication hole 11 has the same height as the height of the respective circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7, and the remaining corner portions 31 b, 31 c, 31 d have a height larger than the height of the respective the circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7. Thus, the circumferential wall 6 b is formed such that the height is continuously varied over a half range of the entire circumferential wall 6 b which extends from the corner portion 31 c to the corner portion 31 d through the corner portion 31 a, and the height is held constant over the remaining half range extending from the corner portion 31 c to the corner portion 31 d through the corner portion 31 b.

Specifically, a plane on which an upper end in the half range of the circumferential wall 6 b of the second core plate 206 which extends from the corner portion 31 c to the corner portion 31 d through the corner portion 31 a is located is inclined relative to a plane P parallel with the base wall 6 a as shown in FIG. 9. On the other hand, a plane on which an upper end in the half range of the circumferential wall 6 b which extends from the corner portion 31 c to the corner portion 31 d through the corner portion 31 b is located lies on the plane P.

Similarly to the oil cooler 100 according to the first embodiment, the oil cooler 200 according to the second embodiment as shown in FIG. 10 can serve for readily recognizing a position of the second core plate 206 in the oil cooler 200 from an outer appearance thereof even after brazing.

Referring to FIG. 11 to FIG. 14, an oil cooler 300 according to a third embodiment of the present invention is explained. The oil cooler 300 has the same construction as that of the above-described oil cooler 100 according to the first embodiment except for configuration of a second core plate 306. Like reference numerals denote like parts, and therefore, detailed explanations thereof are omitted.

As shown in FIG. 11 to FIG. 13, a height of the circumferential wall 6 b of the second core plate 306 in the third embodiment is varied along the circumferential direction of the base wall 6 a as follows. The height at one corner portion 31 b of the pair of diagonally opposed corner portions 31 a, 31 b which is located on the side of the oil communication hole 11 and the height at one corner portion 31 d of the pair of diagonally opposed corner portions 31 c, 31 d which are respectively located on the side of the respective cooling water communication holes 12 are largest and equal to each other. In contrast, the height at the other corner portion 31 a of the pair of diagonally opposed corner portions 31 a, 31 b and the height at the other corner portion 31 c of the pair of diagonally opposed corner portions 31 c, 31 d are smallest and equal to each other. That is, the circumferential wall 6 b of the second core plate 306 is formed such that among the two pairs of diagonally opposed corner portions 31 a, 31 b and 31 c, 31 d, one corner portion 31 a of the pair of diagonally opposed corner portions 31 a, 31 b which is not located on the side of the oil communication hole 11 and one corner portion 31 c of the pair of diagonally opposed corner portions 31 c, 31 d which are respectively located on the side of the respective cooling water communication holes 12 have the same height as that of the respective circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7, and the other corner portion 31 b of the pair of diagonally opposed corner portions 31 a, 31 b and the other corner portion 31 d of the pair of diagonally opposed corner portions 31 c, 31 d have a height larger than that of the respective circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7. In other words, the circumferential wall 6 b of the second core plate 306 is formed such that the height is varied between the corner portion 31 b and the corner portion 31 c and between the corner portion 31 d and the corner portion 31 a, but the height is held constant between the corner portion 31 b and the corner portion 31 d and between the corner portion 31 c and the corner portion 31 a.

Specifically, a plane on which an upper end of a portion of the circumferential wall 6 b which extends between the corner portion 31 b and the corner portion 31 c and an upper end of a portion of the circumferential wall 6 b which extends between the corner portion 31 d and the corner portion 31 a are located is inclined relative to a plane P parallel with the base wall 6 a as shown in FIG. 13. On the other hand, a plane on which an upper end of a portion of the circumferential wall 6 b which extends between the corner portion 31 b and the corner portion 31 d is located lies on the plane P. A plane on which an upper end of a portion of the circumferential wall 6 b which extends between the corner portion 31 c and the corner portion 31 a is located also lies on a plane parallel with the base wall 6 a.

Similarly to the oil cooler 100 according to the first embodiment, the thus constructed oil cooler 300 according to the third embodiment as shown in FIG. 14 serves for readily recognizing a position of the second core plate 306 in the oil cooler 300 from an outer appearance thereof even after brazing.

Referring to FIG. 15 to FIG. 17, an oil cooler 400 according to a fourth embodiment of the present invention is explained. The oil cooler 400 has the same construction as that of the above-described oil cooler 100 according to the first embodiment except that respective core plates 4, 5, 7, 406 have not a rectangular shape but a disk shape in plan view. Like reference numerals denote like parts, and therefore, detailed explanations thereof are omitted.

As shown in FIG. 15, the second core plate 406 includes a disk-shaped base wall 6 a formed with a pair of cooling water communication holes 12, 12 and an oil communication hole 11. The pair of cooling water communication holes 12, 12 are formed in a diametrically opposed relation to each other so as to be symmetric with respect to the central through hole of the base wall 6 a. The oil communication hole 11 is disposed on an outer circumferential side of the base wall 6 a and formed on a straight line perpendicular to a diametrical line of the base wall 6 a on which the cooling water communication holes 12, 12 are formed (i.e., a straight line extending through a center of the base wall 6 a and respective centers of the cooling water communication holes 12, 12).

The circumferential wall 6 b of the second core plate 406 is configured such that a height thereof is continuously varied along a circumferential direction of the base wall 6 a. As shown in FIG. 16, a plane on which an upper end of the circumferential wall 6 b is located is inclined relative to a plane P parallel with the base wall 6 a. Further, the circumferential wall 6 b has a maximum height on a side of the oil communication hole 11, and has a minimum height on a side diametrically opposed to the oil communication hole 11 with respect to the tapered sleeve portion 6 c. In other words, as a distance between the circumferential wall 6 b and the oil communication hole 11 is reduced, the height of the circumferential wall 6 b becomes larger. Further, in the oil cooler 400 according to the fourth embodiment, the minimum height at a portion of the circumferential wall 6 b on the side diametrically opposed to the oil communication hole 11 is equal to the height of the respective circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7.

Similarly to the oil cooler 100 according to the first embodiment, the thus constructed oil cooler 400 according to the fourth embodiment as shown in FIG. 17 can serve for readily recognizing a position of the second core plate 406 in the oil cooler 400 from an outer appearance thereof even after brazing.

Referring to FIG. 18 to FIG. 20, an oil cooler 500 according to a fifth embodiment of the present invention is explained. The oil cooler 500 has the same construction as that of the above-described oil cooler 100 according to the first embodiment except that respective core plates 4, 5, 7, 506 have not a rectangular shape but a circular shape in plan view. Like reference numerals denote like parts, and therefore, detailed explanations thereof are omitted.

As shown in FIG. 18, the second core plate 506 includes a disk-shaped base wall 6 a formed with a pair of cooling water communication holes 12, 12 and an oil communication hole 11. The pair of cooling water communication holes 12, 12 are formed in a diametrically opposed relation to each other so as to be symmetric with respect to the central through hole of the base wall 6 a. The oil communication hole 11 is disposed on an outer circumferential side of the base wall 6 a and formed on a straight line perpendicular to a diametrical line of the base wall 6 a on which the pair of cooling water communication holes 12, 12 are formed (i.e., a straight line extending through a center of the base wall 6 a and respective centers of the cooling water communication holes 12, 12).

The circumferential wall 6 b of the second core plate 506 is configured such that a height thereof is varied along a circumferential direction of the base wall 6 a. As shown in FIG. 18 and FIG. 19, the circumferential wall 6 b of the second core plate 506 includes two circumferential halves that are disposed on both sides of a straight line extending through a center of the base wall 6 a and respective centers of the pair of cooling water communication holes 12, 12 in a case where the circumferential wall 6 b is separated into the two halves by the straight line. One of the two circumferential halves is disposed on a side of the oil communication hole 11, and has a maximum height. The other circumferential half is disposed on a side diametrically opposed to the oil communication hole 11 with respect to the tapered sleeve portion 6 c, and has a minimum height at a portion spaced farthest from the oil communication hole 11 (i.e., at a portion diametrically opposed to the oil communication hole 11). The height of the other circumferential half is continuously decreased to the minimum height. That is, the circumferential wall 6 b of the second core plate 506 has a constant height at the one of the two circumferential halves and a varying height continuously varied at the other thereof. Specifically, as shown in FIG. 19, a plane on which an upper end of the one of the two circumferential halves is located is a plane P parallel with the base wall 6 a, and a plane on which an upper end of the other of the two circumferential halves is located is inclined relative to the plane P. Furthermore, in the oil cooler 500 according to the fifth embodiment, the minimum height at a portion of the other circumferential half of the circumferential wall 6 b is equal to the height of the respective circumferential walls 4 b, 5 b, 7 b of the core plates 4, 5, 7.

Similarly to the oil cooler 100 according to the first embodiment, the thus constructed oil cooler 500 according to the fifth embodiment as shown in FIG. 20 can serve for readily recognizing a position of the second core plate 506 in the oil cooler 500 from an outer appearance thereof even after brazing.

This application is based on a prior Japanese Patent Application No. 2011-139976 filed on Jun. 24, 2011. The entire contents of the Japanese Patent Application No. 2011-139976 are hereby incorporated by reference.

Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims. 

1. An oil cooler comprising: a plurality of core plates stacked on each other, the plurality of core plates each comprising a base wall and a circumferential wall formed along an entire outer periphery of the base wall, the circumferential wall being inclined relative to the base wall so as to outwardly extend from the entire outer periphery of the base wall, the circumferential walls of the core plates which are disposed adjacent to each other in a direction of stacking the core plates being bonded to each other, and oil passages and cooling water passages alternately arranged in the direction of stacking the core plates, the respective oil passages and the respective cooling water passages being formed in a clearance between the base walls adjacent to each other in the direction of stacking the core plates, wherein the core plates comprise at least a first core plate and a second core plate that is different from the first core plate in construction, and the circumferential wall of the second core plate has a height being varied along a circumferential direction of the base wall, and the circumferential wall of the second core plate is partially higher than the circumferential wall of the first core plate.
 2. The oil cooler as claimed in claim 1, wherein the height of the circumferential wall of the second core plate is continuously varied along the entire outer periphery of the base wall, and the circumferential wall of the second core plate has an upper end located on a plane.
 3. The oil cooler as claimed in claim 2, wherein the plane is inclined relative to a plane parallel with the base wall of the second core plate.
 4. The oil cooler as claimed in claim 3, wherein the base wall of the second core plate has a disk shape.
 5. The oil cooler as claimed in claim 1, wherein the circumferential wall of the second core plate comprises a portion at which the height is continuously varied, and the portion has an upper end located on a plane.
 6. The oil cooler as claimed in claim 5, wherein the plane is inclined relative to a plane parallel with the base wall of the second core plate.
 7. The oil cooler as claimed in claim 5, wherein the portion of the circumferential wall of the second core plate is a half range of the entire circumferential wall along the circumferential direction of the base wall.
 8. The oil cooler as claimed in claim 6, wherein the base wall of the second core plate has a disk shape.
 9. The oil cooler as claimed in claim 5, wherein the circumferential wall of the second core plate comprises a portion at which the height is held constant, the portion having an upper end located on a plane that lies on a plane parallel with the base wall.
 10. The oil cooler as claimed in claim 1, wherein the base wall of the first core plate comprises a pair of oil communication holes through which the oil passages are communicated with each other in the direction of stacking the core plates, and a pair of cooling water communication holes through which the cooling water passages are communicated with each other in the direction of stacking the core plates, the pair of oil communication holes being symmetrically arranged with respect to a center of the base wall, the circumferential wall of the first core plate has a constant height over the entire outer periphery of the base wall of the first core plate, and the base wall of the second core plate comprises one oil communication hole aligned with one of the pair of oil communication holes of the base wall of the first core plate, the base wall of the second core plate blocking a flow of oil passing through the other of the pair of oil communication holes of the base wall of the first core plate such that a direction of a flow of oil passing through the oil cooler is changed to a direction perpendicular to the direction of stacking the core plates.
 11. The oil cooler as claimed in claim 1, wherein the circumferential wall of the second core plate includes a portion at which the height is a minimum equal to a height of the circumferential wall of the first core plate. 